Typically, paraplegics, amputees and others with disabilities or who are otherwise bedridden or require permanent or prolonged use of wheel chairs or other support surfaces often have compromised skin integrity. Their skin is subject to long periods of interface with support surfaces such as beds, head rests, wheelchairs or artificial limbs, and is extremely sensitive to the surface qualities of these supports, and specifically the portions that contact their body.
Abrasion and ulceration of skin is commonly caused, and exacerbated, by this prolonged contact. The general population is also susceptible to skin conditions from temporary and prolonged contact with certain fabric materials, but abrasion and ulceration are especially troublesome to susceptible populations. These and similar skin conditions cause pain and discomfort and can also lead to infection and other complications.
Persons who are susceptible to skin damage are aware of the risk rough materials cause with respect to chafing, abrasion and decubitus ulcers. These aware populations often select material surfaces that are as smooth as possible and free from abrasion causing items such as sewn seams, especially proximate areas of vulnerable skin. For example many paraplegics avoid wheelchair cushion covers with sewn seams that could cause abrasion and ulceration.
Sewn seams can lead to chafing by their roughness acting directly upon the skin. However, sewn seams can also increase the coefficient of friction of a surface, in effect gripping the skin. The sewn seam and associated increase in friction causes skin and the tissue below to experience shear stresses that would not be present in a more smoothly constructed seam. These shear stresses can lead to tissue damage such as decubitus ulcers. It should be understood chafing, abrasion, ulceration and skin damage are all risks associated with sewn seams.
Presently, various fabrics, materials, coatings and/or cushions are used to cover support surfaces as required by injury or illness. Many of these items are formed by sewing materials or otherwise stitching such that seams are formed. The seams are generally rough, abrasive or otherwise not smooth. Many users believe that stitching, and the resulting seam, can threaten skin integrity by abrasion and thus would prefer a lack of stitched seams in contact with their body. This aversion to stitching is especially relevant in areas of high contact pressure between the user's body and a support surface.
It is problematic that sewn seams are used to join multiple panels or plies of these materials. However these seams are necessary in the construction of cushion covers, bedding, medical devices, garments and other items, having multiple panels or plies of material. The seams described above can be beneficial by supporting the use of multiple panels or plies to create a material surface with zones of high and low friction. A material surface with zones of low friction and high friction has the potential to decrease the likelihood of discomfort, abrasion and ulceration in many users. Unfortunately the use of sewn seams on these material surfaces often forms a surface that is rough or abrasive and causes discomfort for users and may result ultimately in ulcers or abrasions.
The costs of treating pressure ulcers in the United States alone are staggering. More than 2.5 million pressure ulcers are treated each year in the United States with treatment costs as high as $11 billion. Prevention of pressure ulcers would not only reduce pain and suffering but also medical costs and lost work hours.
Presently, it is difficult to sew plies of fabric that are extremely low in friction, and thus feed poorly through a sewing machine. Such low friction plies tend to slide around in the sewing machine and cause wrinkling and uneven sewn seams in the final product. These very low friction materials are hard to sew properly even using the best sewing machine feeding mechanisms such a walking foot or upper feed dog used in combination with a lower feed dog.
Some aspects of bonding fabrics or dissolving certain materials to aid sewing are known in the prior art. One prior art technique is the use of dissolvable paper to stiffen light materials before sewing. The paper is then dissolved in water after sewing is complete. Unfortunately this technique is not suitable for many situations as fibers are left behind, such as the case where fibers are trapped under stitching or between material. Prior art dissolvable adhesives are illustrated in U.S. Pat. No. 5,094,912 (where an acrylic adhesive is dissolved using a 2% aqueous soda solution), EP 2031032B1, WO2001/046329A1, EP2120228A2, and U.S. Pat. No. 8,361,616 B2.
Unfortunately sewn seams that contact a user's anatomy, either directly or through intervening layers, are often perceived by the user as rough and posing a risk of causing abrasion or ulceration. Many prior art material surfaces that are commonly part of the construction of cushion covers, bedding, garments and medical devices, have sewn seams proximate critical areas of a user's anatomy. For example, prior art shorts often require a sewn seam proximate the ischial tuberosities to assure that the garment fits a user appropriately. Material surfaces wishing to incorporate zones of low friction often have sewn seams on the perimeter of the high and/or low friction zones. These seams detract from the smooth and abrasion free surface desired by users.